Physical characteristics of twin-wire indirect arc plasma

• Study twin wire indirect arc by simulation and experiment with different arc length.
• Arc parameters concentrated in cathode and anode regions but lower in arc column region.
• Arc shape similar to inclined inverted bell and displacement increases with arc length increase.
• Gain kinetic energy of electrons cause arc parameters bigger in anode region.
• Arc parameters rise faster in anode with arc length increase lead to self-adjustment.

In this study, the behavior of arc in a twin-wire indirect arc welding is simulated for arc lengths of 5.2 mm, 6.2 mm and 7.2 mm. The plasma temperature is measured by spectrometric method. The results showed that increase in arc length increase the arc parameters (plasma temperature, current density, plasma velocity, heat flux and arc voltage) of twin-wire indirect arc (TWIA). The change in arc length was found to have little influence on the distribution and the variation in trend of arc parameters in the whole arc region. As the arc length increases, the arc parameters in cathode region increase at a slower rate than those of anode region. This probably is the reason for self-adjustment of TWIA and for the arc stability in a certain range of arc lengths. The temperature of anode region is slightly higher than that in the cathode region and other arc parameters have similar trends. The isotherms are displaced toward the anode side and the shape of TWIA is similar to an inclined and inverted bell. The displacement increases with increasing arc length. The experimental results of plasma temperatures are in good agreement with calculated results which verifies the accuracy of the calculated results.